Converter elements, like wavelength converting layers, are used for converting electromagnetic radiation emitted by light-emitting diodes. When producing a converter element, commonly a matrix material is mixed with phosphors and processed into thin sheets. For example, a polysiloxane matrix reacts with atmospheric moisture, resulting in transformation of the liquid resin into a solid material, also known as moisture curing. During this process, the resin loses up to 30% of its mass due to evaporation of the volatile products of the curing reaction. This leads to the corresponding shrinkage in volume resulting in internal strains within the material and often leading to the formation of cracks as well as warpage of the sheet. Multiple cracks may render the material unusable for its application in converter elements.
Up to now methods for avoiding cracks and warpage are to limit the thickness of the converter layer or to increase the amount of inorganic filler like amorphous silica to reduce the relative amount of the shrinking component. However, thicker converter layers are needed for many applications and too high amounts of fillers may negatively influence the characteristics of the converter layers.